Explanation: Working with cathode-ray tubes (CRTs) requires significant safety precautions due to their inherent design. CRTs are large glass vacuum tubes. The high vacuum inside means that if the glass envelope is compromised—even a small crack—the external atmospheric pressure can cause the tube to violently collapse inwards, or **implode** (B). This implosion can launch glass shards at high velocity. Therefore, extreme care must be taken to **prevent the tube from striking any hard surface** (A), as this could weaken or break the glass. Due to the severe risk of flying glass from an implosion, **safety goggles are essential** (C) to protect the eyes. Gloves are also advisable for better grip, to protect against sharp edges, and to avoid contact with any potentially hazardous materials (like lead in older CRT glass). Since options A, B, and C all describe critical safety measures for handling CRTs, "All of the above" is the correct comprehensive answer.